Microdispensing process and apparatus

Claim 2

Apparatus for dispensing precise volumes of a fluid which is a member of the group consisting of a liquid and a gel comprising: a dispensing conduit connectable to a reservoir of said fluid and terminating in a dispensing tip; means adjacent to at least a segment of the dispensing conduit, providing a passageway, and communicating with a rinsing liquid supply, dispensing pump means communicating with said dispensing conduit for delivering a predetermined volume of said fluid dropwise through said dispensing tip, and discontinuous flushing pump means communicating with said passageway for delivering a rinsing liquid at said dispensing tip and adapted to be actuAted when delivery of said predetermined volume is substantially complete so as to flush from said dispensing tip fluid collected thereon; whereby the rinsing liquid flushes from the dispensing tip any fluid collected externally thereon to reproducibly complete the volume of fluid dispensed.

Claim 3

Apparatus according to claim 1 in which said conduit comprises a hollow needle and said first-mentioned means comprises a cylindrical tubular casing having an inner diameter greater than the outer diameter of said needle, said needle being positioned within said casing so that at least the dispensing tip extends outwardly from the bottom thereof.

Claim 4

Apparatus according to claim 2 in which the flushing pump means delivers the rinsing liquid under pressure and the difference between the inner diameter of the casing and outer diameter of the needle is such as to be effective to prevent flow of the flushing liquid between flushing cycles.

Claim 5

Apparatus according to claim 3 in which said flushing pump means is provided with a hollow side arm projecting from the casing and communicating with said passageway at a point adjacent to a top portion of said passageway.

Claim 6

Apparatus according to claim 4 and comprising further a cap member sealing the top portion of said passageway and accommodating said needle therethrough to maintain the same coaxially within the casing.

Claim 7

Apparatus according to claim 2 and comprising further reagent dispensing means for dispensing a reagent during the dispensing cycle of the liquid or gel responsive to a pre-determined signal.

Claim 8

A process for obtaining precise test fractions from a reservoir containing a fluid which is a member of the group consisting of a liquid and a gel characterized by the steps of: dispensing dropwise a predetermined volume of the fluid for a predetermined cycle through a small-diameter conduit having a dispensing tip and into a collecting vessel, and intermittently delivering at said dispensing tip when the dispensing of said predetermined volume is substantially complete a rinsing liquid flushing from the dispensing tip and into the collecting vessel any fluid collected on said dispensing tip and thereby reproducibly completing each collecting cycle.

Claim 9

A process for obtaining precise test fractions from a reservoir containing a fluid which is a member of the group consisting of a liquid and a gel characterized by the steps of: dispensing dropwise a predetermined volume of the fluid for a predetermined cycle through a small-diameter conduit having a dispensing tip and into a collecting vessel, and intermittently delivering at said dispensing tip when the dispensing of said predetermined volume is substantially complete a rinsing liquid flushing from the dispensing tip and into the collecting vessel any fluid collected on said dispensing tip and thereby reproducibly completing each collecting cycle.

Claim 10

The process of claim 7 wherein the rinsing liquid comprises a reagent for use in chemical analysis of the test fraction.

Claim 11

The process of claim 7 further characterized by the step of dispensing into the test fraction a liquid scintillation reagent simultaneously with the delivery of the rinsing liquid.

Claim 12

In an apparatus for continuously and automatically obtaining precise test fractions from a liquid or gel reservoir for further analysis and including a rack containing a plurality of collection vessels, a delivery head mounted above said vessels and means for moving delivery of liquid or gel from one vessel to the next at a pre-determined dispensing cycle, the improvement comprising: a supporting block attached to said head; a small-diameter conduit having a dispensing tip; a tubular casing of larger inner diameter sheathing a portion of said conduit and providing an annular passageway therealong; means connecting the conduit to the casing in coaxial relationship so that the dispensing tip extends beyond the bottom of the casing; a side arm projecting from the casing and communicating with said passageway; means in said block cooperating with said conduit, casing and side arm to support the same in readily removable relationship; means connecting said side arm to a flushing liquid source; pump means for delivering flushing liquid to the side arm; and timer means for automatically actuating the pump means at a pre-determined time in each dispensing cycle, whereupon the flushing liquid flows through said passageway and rinses from the dispensing tip any liquid or gel collected thereon to complete each test fraction.

Claim 13

In an apparatus for continuously and automatically obtaining precise test fractions from a liquid or gel reservoir for further analysis and including a rack containing a plurality of collection vessels, a delivery head mounted above said vessels and means for moving delivery of liquid or gel from one vessel to the next at a pre-determined dispensing cycle, the improvement comprising: a supporting block attached to said head; a small-diameter conduit having a dispensing tip; a tubular casing of larger inner diameter sheathing a portion of said conduit and providing an annular passageway therealong; means connecting the conduit to the casing in coaxial relationship so that the dispensing tip extends beyond the bottom of the casing; a side arm projecting from the casing and communicating with said passageway; means in said block cooperating with said conduit, casing and side arm to support the same in readily removable relationship; means connecting said side arm to a flushing liquid source; pump means for delivering flushing liquid to the side arm; and timer means for automatically actuating the pump means at a pre-determined time in each dispensing cycle, whereupon the flushing liquid flows through said passageway and rinses from the dispensing tip any liquid or gel collected thereon to complete each test fraction.

Claim 14

Apparatus according to claim 10 in which the difference between the Inner diameter of the casing and the outer diameter of the conduit is such as to be effective to prevent flow of the flushing liquid between flushing cycles.

Claim 15

Apparatus according to claim 11 in which the flushing liquid comprises a reagent for use in chemical analysis of the test fractions.

Claim 16

Apparatus according to claim 10 and comprising further a reagent spout; means for removably and adjustably connecting said reagent spout to the supporting block; means connecting the reagent spout to a liquid scintillation reagent source; and second pump means for delivering the scintillation reagent to said spout; said timer means automatically actuating said second pump means to dispense into the test fraction simultaneously with the delivery of the flushing liquid a fixed amount of the liquid scintillation reagent for use in radioactive assay of the test fractions.